Ternary uranium alloy



TERNARY URANIUM ALLGY Frank A. Rough and Henry A. Salier, Columbus, Ohio,

No Drawing. Application July 14, i954, Serial No. 443,450

2 Claims. (31. 75-134 This invention deals with a uranium alloy, and in particular with a uranium alloy containing chromium.

Uranium alloys are being used nowadays for many purposes. One of the most frequent applications of uranium is infuel elements for neutronic reactors such as are disclosed, for instance, in Fermi and Szilard U. S. Patent No. 2,707,656 based on application Serial No. 568,904 filed on December 19, 1944. In the case that the reactors are operated for the production of power, U or a U -enriched uranium is employed as the fuel material. One type of power reactor uses fast neutrons for bombarding the U -containing metal which has been cast into an assembly of a plurality of iron tubes so that it surrounds each tube completely. A liquid coolant, preferably sodium metal, flows through the iron tubes; a moderator is not employed in this type of reactor. The tubes normally have a length of at least 2 feet and their average outside diameter is about /s inch. It has been found very difficult to have a fuel material for these reactors which has all the characteristics required of such material and also has enough fluidity to fill all the empty spaces in such a cooling-tube assembly.

Uranium-chromium alloys, and in particular the eutectic which contains 5.0% by weight of chromium and which melts at 868 C., have been examined for the aboveoutlined purposes. However, these alloys require rather high casting temperatures at which they were found to attack the iron tubes.

It is an object of this invention to provide an alloy which has a melting point low enough so that the attack of the iron tubes during casting is prevented.

It is another object of this invention to provide an alloy which, when melted, has a low viscosity and a good castability'so that all spaces of any intricate mold, such as, for instance, the cooling-tube assembly described above, are completely filled out.

It is another object of this invention to provide an alloy which, when cast around iron, yields a good bond nitcd States Patent U" 2,735,761 Patented Feb. 21, 1956 2 therewith so that a unit of good heat conductivity is obtained.

It is finally also an object of this invention to provide an alloy which has a low neutron capture cross section.

These and other objects are accomplished by mixing iron with the uranium-chromium eutectic whereby an alloy of a reduced melting point is obtained. While contents of iron ranging between 0.5 and about 10% by weight are beneficial, a quantity so as to yield a content of about 1% in the final alloy is preferred; higher quantities did not bring about any improvement of the various characteristics, but impaired the ductility to a certain degree. The alloy containing approximately 94% by weight of uranium, 5% of chromium and 1% of iron has a melting point of 760 C., which is 108 C. lower than that of the uranium-chromium eutectic.

The alloys can be prepared by any method known to those skilled in the art. One preferred way of producing them comprises induction-melting the iron, uranium and chromium in a vacuum until a homogeneous alloy is obtained. The alloy may then be cast into the shapes desired of the fuel elements or other articles.

It was found that the alloy containing 1% by weight of iron showed excellent castability and had all the characteristics desirable for cast fuel elements of neutronic reactors.

In the investigations leading to the alloy of this invention additions of manganese and nickel were also examined as to their usability for the purpose of this invention, and it was found that they, too, lower the solidus point of a uranium-chromium eutectic but that they have only very little effect on the liquidus point. Since, however, the solidus point is the more important of the two transformation points between solid and liquid state for casting purposes, manganese and nickel did not prove as beneficial as additives as the iron. Moreover, the alloys containing the manganese and the nickel, respectively, were found to be less ductile than the iron-containing alloy.

It will be understood that this invention is not to be limited to the details given herein but that it may be modified within the scope of the appended claims.

What is claimed is:

1. As a new composition of matter, a ternary alloy containing about 5% by weight of chromium, from 0.5 to 10% of iron and the remainder uranium.

'2. The alloy of claim 1 wherein the iron content is about 1% by weight.

References Cited in the file of this patent UNITED STATES PATENTS 2,213,207 De Golyer Sept. 3, 1940 2,220,083 De Golyer Nov. 5, 1940 

1. AS A NEW COMPOSITION OF MATTER, A TERNARY ALLOY CONTAINING ABOUT 5% BY WEIGHT OF CHROMIUM, FROM 0.5 TO 10% OF IRON AND THE REMAINDER URANIUM. 